Drill accurately from opposite edges of a workpiece
To drill a 1⁄2 " hole through a 6"-wide workpiece you'll need to drill from opposite edges and have the holes meet in the middle. Doing that requires an accurately adjusted drill press. First, make sure it bores holes exactly 90° to its table. Then, chuck in a brad-point bit and set the drill-press-table fence to center the bit on the thickness of a scrap the same thickness as a bed rail. To do this, with the machine off, press the point of the bit into the edge of the scrap piece. Turn the scrap end-for-end and place the opposite face against the fence. Plunge down the bit again and check the positions of the two indentations. Tweak the fence location and try again until the indentations fall in the same spot, as shown. Now that you know your bit will be perfectly centered on the edge of the stock, you need only clamp to the fence a stopblock 11⁄4 " from the center of the bit. The holes will line up precisely.